In nonvolatile memories (NVMs), a typical reference for sensing is based on one or more memory cells constructed in the same way as the memory cells used in an array of the memory. This is beneficial for tracking the characteristics of the memory cells of the array. One difficulty has been disturbing the state of the reference cells. The reference cells would normally be expected to be divided between programmed and erase. These programmed and erased reference cells would then be used in generating the reference. When these referenced cells are disturbed and lose electrons, the reference changes which reduces the effectiveness of the reference.
Accordingly, it is desirable to sense using a reference that is not susceptible to being disturbed.